1. Field of the Invention
The present invention relates to an inkjet recording apparatus that prints onto a recording medium such as copying paper by discharging ink in response to an image signal.
2. Description of the Related Art
Conventionally, an inkjet recording apparatus that prints onto a recording medium such as copying paper by discharging ink which fills up an ink chamber in response to an image signal has been proposed. In this type of recording apparatus for example, the inkjet head 90 as disclosed in U.S. Pat. No. 5,471,232 has been used as an ink discharge means.
FIG. 1 shows the above-mentioned inkjet head 90. This inkjet head 90 is comprised by spacers 94 fixed to a nozzle plate 92 where a plurality of nozzle holes 91 are formed. Said spacers 94 divide the chamber to form the ink chambers 93 which correspond to each nozzle hole 91. A vibration plate 95 is fixed to the lower portion of the spacers 94. Island portions 96 formed on the lower surface of this vibration plate 95 by means of electroforming are fixed to the top surface of a piezoelectric member 97.
In an inkjet head 90 comprising the above-mentioned construction, the piezoelectric member is made to expand and contract by applying a voltage to the piezoelectric member 97. Then, the deformation of the piezoelectric member 97 is efficiently transferred through the island portions 96 to the vibration plate 95 to either expand or contract the vibration plate. Thereby, ink inside the ink chambers 93 is pressurized by means of the vibration plate 95 after which ink droplets are discharged from the nozzle holes 91.
However, because there are a large number of members and assemblies used to form the ink chambers 93 for said inkjet head 90, irregularity in the dimensions and assembly precision of each ink chamber 93 easily occurred. As a result there are other problems such as changes in the ink pressurization characteristics due to the vibration plate and uneven diameter of the ink droplets to be discharged occurring between the ink chambers 93. Furthermore, in a type of inkjet head that pressurizes the ink chambers 93 by means of the vibration plate 95, the vibration of the piezoelectric member 97 for one ink chamber 93 is transferred to the ink housed inside the adjacent ink chambers 93 through the vibration plate 95 making the surface tension of the ink unstable. Thereby, a problem occurs in which ink leaks from the ink chamber that should not discharge ink.